Solid water-in-rosin paper size



June 30, 1942. ARLEDTER E I'AL SOLID WA'IER-IN-ROSIN PAPEB SIZE Filed Sept. 2, 1938 2 Sheets-Sheet 1 m m M aa ,4 r d v ZQ N. m f V. B

June 30, 1942. F. ARLEDTER ETAL 2,288,060

SOLID WATER-IN-ROSIN PAPER SIZE Filed Sept. 2, 1938 2 Sheets-Sheet 2 W 'Q ATTORNEY Patented June 30, 1942 v UNITE SATES PATNT OFFIC soLm WATER-IN-ROSIN PAPER SIZE Fritz Arledter, Cologne-Kalk, and Alois Allina, Vienna, Germany, assignors to Gustav Staelin,

Lai ihmont, N.- Y.

Application September 2, 1938, Serial No. 228,080 4 Claims. (01. 106-230 t The present invention relates to rosin paper size and, more particularly, to aprocess for producing a solid, substantially non-saponifled rosin paper size readily dispersible in water' and the product thereof and to a process for producing a dilute size solution from the aforesaid concentrated solid rosin size.

In the sizing of paper, two types of rosin size,

generally speaking, have been in common use.

The type which has been in use for the longest time has been commonly knownas neutral size and the otherhas'been known asfree rosin size. By reducing the amount of alkali used to saponify the rosin, the amount of free rosin present in a size can be increased from about 8.2% in completely saponified rosin to about 52.6% in the free rosin size. The minimum of 8.2% free rosin in completely saponified rosin size has been obtained a. a result of the presence of about. 8.8%

' of unsaponifiable material in the original rosin.

However, it is to be noted that as ,the proportion of free rosin increasesfdimculties arise in the utilization of the size in the paper mill. This was especially true of rosin sizes containing more than about'35% free rosin. Unless the dilution of sizes containing more than. 35% free rosin.

was controlled with meticulous care, the size decomposed with the formation of a 'coarse suspension of rosin which was not only inefficient, but was certain to cause trouble.

Since the sizing of 'paper may beconsidered to be an operation in which the fibers of the paper havebeen given a coating of water-ineter 'of the first globule be 1 centimeter or 1 micron. f

A paper size solution of the class of free rosin sizes'having up to about 45% free rosin has been described in "U. s. Patent No. 1,882,680 to Wieger.

This patentee describes a process in which 98 kilograms of a rosin having a saponification number. of 165 are melted and to which small quantities of water are added to cool the material. If desired; small amounts of alkali; say

about 0.1 to 3% are added. At a temperature of about 80 to 90 C., a hot solution of 2% casein in 25 liters of water containing 200 grams of caustic soda is added. More water is added 'in order to cool the material. This process produces a size which usually contains about 55% water and therefore must be shipped in expen-' sive water-tight drums. Furthermore, when this size is dispersed in water, the diameter of the particles on, the average is of the order of '1 art are very sensitive to local mill conditions of soluble material, it is manifest that the smaller the particles of the coating substance, the greater surface of paper will be coated with a given amount of size. This-is readily proven mathematieally by considering the comparative surface of two globules of rosin one with a diameter of 1 centimeter and the other witha diameter of 0.25 centimeter.

The first will have a surface area of about 3.142 square centimeters and a volume of about 0.5236 cubic centimeter, while the second will have a surface area of about 0.197 square centimeter and a volume of about 0.0082 cubic centimeter. Thus, if the first globule be divided into. about 63.8 globules each having a diameter of about 0.25 centimeter, the.combined surfaces of the 63.8 globules will be about 12,372 square centimeters. In other words, the same volume or weight of rosin if subdivided into particles having 0.25, the diameter of the original globule will. cover asurface 3.97 tiines as great. The above calculations hold whether the diamsaltcontent of the water, pH of the water, and similar variables which are well-known to those skilled in the art. 3

A more recent development in the art of producing'paper size is the process and product described in several foreign patents notably the British Patent No. 424,230. These foreign patents disclose a process for the production of a solid, readily soluble rosinwhich is supposed to.

be an improvement on Wieger. The process involves melting rosin and then cooling the melted rosin to'about 100 C. To the cooled rosin an amount of water equivalent to about 10% of the weight of the rosin is added, followed by the addition. of an amount of casein equal to about- .3% of the rosin and an amountof ammonia disclosure, these patentees' claim to produce a' product which is a solid form and,capable of equal to about 1.2% of the weight of the rosin. While soluble rosin was not known prior to this being kept indefinitely, but which as distinct from natural rosin,-is soluble in water. Thus,

the art has been confronted with the problem I of providing a more emcient rosin size proclikewise been confronted with the problem of the sensitivity of conventional prior art sizes .to local sizing conditions and oi the complexity and dimculties of operations. Although many attempts have been made to solve these problems, none, so far as we are aware, has resulted in a wholly prior art products. proved size rosin requires a smaller amount of satisfactory solution especially when carried into practice on an industrial scale.

We have discovered a process for preparing size rosin in the solid state which is insoluble" in water and is readily dispersible therein as a dispersion of extremely fine particles. A smaller amount of our improved size rosin will'coat a .given weight of paper and permit less penetration of ink as determined by standard methods than A given weight of our imalum for, precipitation in' the paper being sized.

carried out at-higher pl-lvalues with the same margin of safety when using our improved size rosin than is conventional practice. Our improved size rdsin likewise is capable of producing The sizing process in the paper mills'may be taken on line 2 2 of Fig. 1 looking in the direction of the arrowi Generally speaking, our improved process the production of size rosinin the solid state and readily dispersible in water to form a sizing solution having particles the average diameter of which is less than about 1 micron, comprises emulsifying a small amount of water in rosin in the molten state in the presence of carefulhr regulated critical amounts of protective colloids, and then reversing the type of emulsion to a rosin in water emulsion at the time of sizing ent invention, a water-in-rosin emulsion is formed by melting collophony with of without additions of natural or synthetic resins, fatty oils,

slowly pumped preferably through a distributor.

placed in the bottom of a tank or autoclave containing the resinic material, into the collophonic material. The liquid resinic material is stirred to ensure intimate and homogeneous mixing of the water with the rosin. Small amounts .of

rosin size emulsion containing from-40-to 90% unsaponifled resin acids or free rosin. Thus, the disadvantages of the prior art products, such as the necessityof using water-tight barrels and containers, the costly excess weight due to the presence of water of solution, and the sensitivity of prior art size rosins containing appreciable amounts oi iree rosin to local sizing conditions, are overcome by the product of. our new process.

'In addition, the-saving in the quantity of size rosin consumed andgthe amount of alumused is appreciable when our improved size rosin is used.

Ltis an object of the present invention to provide a process for producinga waterinsoluble,

solid size rosin containing appreciable amounts.

of unsaponiiled resin acids and readily dispersible in water'.

It is another object of the present invention to provide a process for producing a water-insolro'sin and readily dispersible in water.

It is a further object of the present invention to pro'videia process for producing water-insolu ble, solid size rosin coiit'aining over 40% free rosin and readily dispersible in water to form a sizing solution having pafisicles of free rosin size with an average diameter of less than 1 micron.

The presentinvention also contemplates the provision of a process for producing a dilute aqueous emulsion from the concentrated solid size gel and an apparatus therefor.

It is also within the scope of the present invention to provide a sized paper having a thinner film of rosin size than prior art papers o f-comparablgweig'ht and of comparable constituents,

1 having equivalent resistance-to ink penetration.

, Otherbbjects and advantages will become apparent from the following description taken in "conjunction with the accompanying drawings, in

which Fig. 1 is a side elevational view of a converter embodying the principles oi the present invention with parts broken'away ior the sake of clarity, and I Fig. 2 is a sectional view of a converter embodying the principles of the present invention I h uble, solid sizeirosinjcontaining at least 40%-free v pheres;

protective colloids are made.

of protective colloid added is between about 3 and about 20% and preferably about 4 to about colloid at practically the same rate with .undistrib lumps in the water -in-rosin emulsion. The temalkali, say about 0.1 to about 0.5% by weight,

are introduced either before the addition of the water, with the water, .or immediately after the addition of the water; With the slow addition of the water and the thorough stirring and mixing of the water in the resinic material, a waterin-rosin emulsion is formed. After the formation of the water-in-rosin emulsion, the temperature of the emulsion is preferably cooled to about to about C., and additions of one or more The total amount 10%. The protective colloids may be added individually or in combination and as a powder or in solution. The addition ofth'e protective colloidv must be carried out with care to ensure that the water-in-rosin emulsion takes up the which the colloid is introduced into the emulsion. We have found that satisfactory results are obtained by introducing the colloid into the emulsion of .water-imrosin through a distributor located in the bottom of the tank. .During the introduc-:

tion of the colloid, the water-in-rosinemulsion shouldbe stirred so that the colloid is thoroughly mixed with the emulsion to forma homogeneous H mass. Care should be exercised to prevent the addition of the colloid at temperatures at which the 001101 denatures or at a rate at which the d colloid agglomerates and forms edfor this purpose, care being taken that the pressure does not rise above about ten atmos- Excess ammonia may be withdrawn from the mixing vessel and recovered for further use. We have found th:'1"t 1ess than about 50% for In accordance with the principles of the presof the 'total ammonia added to the resinic material is retained in the solid rosin size product; the remainder being vaporized and recovered if desired. Analysis of the solid rosin size with a determination of the alkali content, has shown We have found that satisfactory results are obtained when starch, dextrines, animal'glue, gelatine, andcasein are used as protective colloids. Good results are likewise obtained by the use of synthetic emulsifiers, such as triaethanolamine stearate. Of course, combinationsof two or more of the various colloids and/ or emulsifiers referred to hereinabove may be used, and in fact exceptionally good results have been'obtained with mixtures, such as the following: a mixture of protective colloids amounting to about 3 to about of the weight of the resinic material and containing about 2.8% starch, about 1.9% animal glue or gelatine, and about 3.0% casein.

An alkaline solution containing solids and containing a quantity of animal glue or gelatine equivalent to about 2.3% of the weight of the rosin and a quantity of casein equivalent to about 4.5% of the weight of the rosin produces a very' good result, while other combinations include one containing 2.5% starch and 3.5% casein. and

another 5.3% starch and 2.5% animal glue or gelatine, wherein all quantities are based on the weight of the rosin. The use of different protective colloids or combinations has a marked effect upon the size of the particles and the dis-* tribution of particles in groups having various diameters and also upon the sizeof the precipitat-ed particles after the addition-of alum in the sizing process. For example. in the presence of starch animal glue,. gelatine, and the like in the emulsion, the particles flocculated by the addition of alum in the sizing process are very .fine. On the other hand, the use of casein alone results in the flocculation of the rosin in particles of comparatively large size. Casein can also assist in the flocculation in the presence of alum of materials which .otherwise would stay in 'solution or suspension. v

As alkaline agents in the formation of. the water-in-rosin emulsion, soda ash, caustic soda and sodium aluminate, and similar alkaline substances. may be used. Ammonium carbonate may be substituted for a portion, up to about 50%, of the aqua ammonia.

To obtain special effects, it is often advisable of phenol and pH of about 5.5 to 4.7 in sizing with the prior art products. However, when sizing with our improved size rosin, it is only necessary to reduce the pH to about 5.5 to about 6.5 in order to sizewith the same safety as when using conventional prior art. products. I 1

For the purpose of giving those skilled in the art a better understanding of the process for producing our improved water-insoluble, solid size rosin, in accordance with the principles of the present invention, the following illustrated examples are given:

Example No, 1

" About 1000 kilograms of molten rosin are thoroughly mixed in a container, for example, an autoclave, with about 5 kilograms of soda ash (NazCoa) or a mixture of about 2.5kilograms ofcaustic soda and about 2.5 kilograms of sodium aluminate. -About 10 kilograms of water in either aqueous or vapor form are introduced preferably through a distributor located at the bottom of the container and provided with numerous small openings. The temperature is adjusted to about to about 100 C. and the water thoroughly incorporated in the resin in the presence of thealkali to form a water-inrcsin emulsion. The temperature of the waterin-rosin emulsion is then reduced to below about 100 C. and about kilograms of a starch solution containing about 45%-55% starch is stirred into the resinic material. The starch solution may be made up of equal parts of .com starch and potato starch hydrolyzed by 150 grams of biolase, theactivity of which has been reduced by the addition of inhibitors such as 5% alkali or acid salts, that is salts which in aqueoussolution have a markedly acid reaction. The starch solution is added slowly and not at a rate at which it-cannot be taken up by the emulsion. Usually 5 to 30 minutes is required to introduce this amount of'starch solution into the emulsion. The introduction of the starch should be accompanied by thorough stirring. When all the starch solution has been added, about kilograms of an alkaline solution containing about 45 kilograms of a mixture of about 30 kilograms of casein and about 15 kilograms animal glue or gelatine and about 1.5 kilograms of caustic soda is introduced with the same precautions as were exercised in-the introduction of the starch. In addition, the temperature of the protective colloicls should be maintained at about 55 C. and

extreme care exercised to introduce the colloids at approximately the rate at .whichthe colloids are dispersed in the emulsion. After the introduction of the colloids, the speed of agitation maybe increased (the viscosity of the emulsion decreases and thus the expenditure of power does not become prohibitive) and the stirring continued for a short time, say about 20 minutes. Then about 50 kilograms of aqua ammcnia containing about 33% ammonia is introducedunder pressure through the aforemen-" ti'oned distributor. After the whole of the ammonia has been introduced and has reacted been determined that onlyabout 0.8 to about 1.0% of the ammonia (NI-I3) added to the rosin remains in the product.

Example Nb. 2 h To about 1000 kilograms of rosin having a "saponification value of about 165, and in the molten state, about 7 kilograms of water and kilograms of alkaline casein or other protective colloid, solutions are added. The rosin is thoroughly agitated or stirred during the introduction ofthe casein wtih the same precautions as were observed in Example No. 1. Then,

kilograms of an ammonium salt, such as ammonium carbonate in about kilograms of water, are introducedthrough the distributor. After the addition of the ammonium salt, at least40 kilograms of a 30% starch solution is mixed with the water-in-rosin emulsion andthoroughly dispersed therein. During the in-' troduction of the starch solution, the temperature is regulated to about 50 C. After the addition of the starch, the resin emulsion isidrawn off into containers. 1

Example No. 3

About five kilograms of caustic soda and about 20 kilograms of water are thoroughly incorporated in about 1000 kilograms of liquid rosin at about the melting temperature ofthe rosin. The mixture is stirred vigorously until a water-inrosin emulsion is obtained, whereupon about 80 kilograms of casein, or. casein and starch r casein, animal glue and starch in the powder form are mixed .with the water-in-rosin emulsion. After the colloid has been added to the emulsion and dispersed therein, about kilograms of caustic soda in about 60 liters of water are thoroughly mixed with the emulsion. After a further stirring "for a short time, say about 20 minutes, 50

kilograms of aqua ammonia containing about 33% ammonia are mixed with the emulsion and thoroughly dispersed therein with vigorous stirring. The size, 1' sin is then drawn of! into containers and allowe to solidify.

Example No. 4

A modified process for producing solid size rosin in accordance-with the'principles of the present invention includes the production of the size rosin in accordance with Examples Nos. 1

,to 3 and the addition of about 20 kilograms of triaethanolaminejstearate or the like immediateh after the addition of the ammonia.

Example No. 5

A furthermodiflcation comprises the addition of about 50 kilograms or more of saponified and/or similar products to the molten rosin.

The diameter of the particles of the solid size rosin produced in accordance with the principles of the present invention, when dispersed in water, will average less than 1 micron. In fact, solid 'stearine, fatty acid products, waxes, paraflin rosin sizes made in accordance with the principles of the present invention will often disperse in -water to.form suspensions in which about 50% more or less of the particles are such sizethat they are invisible under the ultraconvert the solid concentrated rosin size gel of the present invention to a dilute suspension like size gel produced in accordance with the principlesof the present invention is subjected to temperatures reached in the vicinity of steam coils, for example, for any extended period of time, and the critical volume of the particles of rosin size is affected adversely. Thus, it is necessary to provide a means formelting the solid rosin size in which it is possible to remove the size from the zone of relatively high temperature as soon as the size is fluid enough to flow.

"I'herate of the introduction of the necessary diluent water into the molten rosin size must be controlled within critical limits to insure that the rosin particles will not flocculate. In addition; the temperature of the water and the temperature'of the rosin-water mixture during the transition from the gel stage to the sol stage must be controlled-within critical limits. Furthermore, the temperature of the mixture of rosin size anid water must be controlled within critical limits during the transition from the gel" stage to the "sol" stage and during dilufio? to avoid flocculation of the rosin 'size par- In addition to the importance of maintaining the fine state of division in which the rosin size is present in the "gel" stage during the transition to the sol stage or condition, the power cone. 7

sumption is also an important factor, particularly from a practical and industrial point of view. For example, the power consumed in bringing one of the conventional concentrated aqueous size solutions 'or suspensions to the dilute condition of a dilute size suspension, 1. e., a size milk, is considerably greater than that necessaryto bring'the solid -rosin size gel! of the present invention from the gel"' condition to the "sol stage, and then to the dflute concentration suitable for use in the beater when the apparatus .of the present invention is employed. As those skilled in the art know the power consumed in mixing varies as the cube of the rate of rotation. Thus, a mixer now in use mixer of the converter hereinafter described operates ata rate of 20 to 80 R. PJM. and prefer- V ably at a rate of 40 R. P. M. f

nearly all the .particles of the size are of such diameters as tobe invisible when examined at The time required to dilutea prior art concentrated aqueous suspension of rosin size or to Wise is an important industrial factor in the practical, application of rosin to the sizing of paper. The fact that free rosin size'isdiflicult to suspend in dilute suspension even when starting from concentrated suspensions is well known in the art. This difficulty has been overcome in a practical manner in the following way It is known that when molten rosin is divided into However, in the presence of dispersants molten rosin readily goes into suspension in warm water.

- mixer with the time required to convertthe concentrated rosin size gel of the present invention to a dilute aqueous suspension or so1."

A mixing time of 120 minutes was required to produce a dilute size suspension from a concen-' trated size suspension in a conventionaltype of apparatus. On the other hand, dilute siz sols or suspensions have been made from the solid concentrated rosin size gel embodying the present invention in about 30 to about 70 minutes in the apparatus described hereinafter. In other words, an equivalent amount of dilute'size sus pension or size milk can be made from the concentrated solid size gel in 25 to about 50% "of the time heretofore required.

, In general, the preparationof dilute size ready for use in the beater from solid concentrated size gel of the present invention is advanis divided into a plurality of compartments, pref erably three, 2 I, 22 and 23. These compartments are provided with a plurality of-orificesor out-' lets 24 for the purposeof controlling the rate of introduction of the diluent water into the molten rosin size gel or suspension. For example, ,one compartment is provided with sufficient orifices to permit a unit quantity of diluent water to flow into'the converter in a givenperiod,

' ment is provided with suflicient eflluent capacity tageously carried out in an apparatus, such as is shown in Figs. 1 and 2.

The concentrated solid rosin size "gel" is melted in the hopper and flows into the mixing tank. Water for dilution is added at critical rates and at acritical temperature from a supply tank. The rate of mixing may be increased as the viscosity of the size-water mixture decreases as the size passes from the gel stage to the sol stage.

For the purpose of giving those skilled in the art a'better understanding of the principles of the present invention, the apparatus for making inlet 3 and an outlet 4 for condensate. The melting pot or hopper I: is supported over a feed hopper 5 by a plurality of members 6 and I. Rosin size 8 in hopper l rests on and against steam coil 2. As soon as the rosin size has been say about 15 to 20 minutes. A second compartto allow the unit quantity of diluent waterto flow into theconverter in, say 0.5 the time. A third compartment is provided with suflicient efliuent area to permit the passage of the unit quantity of water into the converter in, say 0.33 to 0.25 the time required for the emptying of the first compartment. By controlling the addition-of the diluent water in this critical manner, the transition of the concentrated molten rosin size "gel to the sol stage and then to the dilute sol stage is accomplished without deemulsifying the suspension and without the "flocculation or agglomeration .of the size particles.

By combining this critical control of the rate of addition of the diluent water, viz., the rate at which the gel" is capable of taking up water and passing to the sol stage, with the critical control of the temperature of the water, of the rosin and of the resulting suspension, it is possible to produce rosin size emulsions (sols) embodying thepresent invention and having rosin size particles averaging less than 1 micron in diameter and having 50% or more of the particles invisible at a magnification of 2500 diameter.

An important feature of the converter-9 is the means for agitating and mixing the molten size and the diluent water. It is of majbr importance, as those skilled in the art appreciate, to produce size suspensions with uni-form texture, .i. e., size suspensions which'have a uniform concentration Y of size particles of uniform diameters. This brought to a temperature at which it is fluid,

it drips or flows into a feed hopper 5. In this way the water-in-rosin gel is not exposed to the-de-emulsifying effect of the relatively high temperatures existing in the vicinity of the steam coil long enough toresult in breaking down the emulsion. Forbest results, the'temperature of the water-in-rosin emulsion should be maintained between about C. and about C., and preferably at about 55 C. The molten size "ge passes from the feed hopper 5 into converter 9 by means of feed hopper outlet [0. and converted inlet II.

The converter 9 comprises a casing l2 provided with an inlet H, a steam jacket IS, an outlet H, a dump valve l5, and shaft seals and bearings l6 and ll.- A means for determining the temperature of the contents of the converter, such as a thermometer l8, and a pressure gauge l8a are also provided. The converter is likewise provided with a water manifold or distributor l9 and an agitator 22. The water manifold or'distributor l uniformity of texture is obtained readily, rapidly and consistently as a result of the unique form of mixing or agitating elements. Converter 9 is provided with an agitator 20 comprisingshaft 25 and a plurality of blades 25. From the bottom of the converter 9 a series of stationary blades 21 rise between which the movable blades 26 pass. The blades 23 are disposed around the axis of the shaft -25 in such a manner thata line drawn through the outer extremitiesof the blades describes a curve around the shaft as an axis similar to the conventional sine curve. The blades 26 also are disposed onI-the shaft 25 withthe horizontal axes of the blades forming an angle less than a right angle with the horizontal axis of the shaft 25. Due to the positioning of the blades with respect to the shaft and Ito each other, the rosin-water mixture is constantly moved from the ends. 28 and .29 of the converter to the center thereof and flows back pass .through the cycle again and is driven by spur gear 31 keyed to countershaft 38. On countershaft 38 are mounted'pulleys 39, 40 and ll, of which 39 is keyed to the countershaft 38, while pulleys 40 and 4| are free to revolve thereon. Pulleys 39, 40 and 6| are preferably of the same diameter and predetermined speeds of rotation of pulley 39, are provided by means of pulleys of different diameter mounted on the mainshaft (not shown). Of course, other means of varyingthe speed of rotation may be provided, but we have found that the method herein described above gives satisfactory results.

Since the gears 36 and 31 have a fixed ratio,

the pulleys of the main driving shaft are proportioned to give 'the desired R. P. M. of the agitator, via, 20 to 80 R. P. M., and preferably 20 to 40 R. P. M.

The steam jacket I! is provided for the preparation of modifled sizes containing components having a higher melting point than the unmodi- 'size for .special effects. The condensate produced by the steam escapes through outlet 43. A safety valve 42: and a pressure gauge I80 are also provided.

To avoid spattering and splashing of the dilute size suspension. and to provide a valve which does not freeze and is readily cleaned, we have found that a dump valve similar to that illustrated in Fig. 1 meets all requirements. Valve 4 l comprises a splash box 44 having an outlet 45 and a converter closure plate 48. The valve is pivoted on shaft 41 and actuated by lever 48. Slidably mounted on lever 48 is counterbalancing weight 49. By this construction, a readily cleaned closure control and rapidly opened valve is provided, and likewisethe splashing and spattering of the size-milk is avoided.

The diluent water may most conveniently be heated and stored in a supply tank 50 erected near, and preferably over, the converter. The supply tank is provided with a water inlet 5|, a water overflow 52, and a discharge 53. The discharge 53 is preferably provided with a threeway valve 54 providing three different rates of discharge. A flexible conduit 55 is provided to carry the diluent water from the valve to the water manifold J9. Of course, other means for providing different rates of discharge, such as three separate valves serving three separate conduits and similar means, may be employed. The flexible conduit 55 may be moved from one compartment of the manifold is to another as the operation proceeds. The supply tank 50 is provided with a steam inlet 58 for the introduction of steam into the diluent water for the purpose ofraising the temperature of the water when necessary. Of course, a steam coil could replace the open steam line if desired. A thermometer 51 and a gauge glass 58 are also included in the equipment of the supp y tank.

We have found that the solid concentrated size ge produced in accordance with the principles of the present invention can best be d1- luted in the following manner. Comminuted size is placed in the melting hopper i and steam introduced into the coil 2. The'size on melting immediately flows ordrips down into the feed hopper 5 and thence through the hopper outlet II and the converter inlet ll into the converter 9. As soon as size is introduced into the converter a, the agitator is started. Meanwhile the required amount of diluent water has been heat-- 5 perature of the diluent water is regulated to be just sufficient tomaintain a temperature of about 40 C. to about 60 C. in the finished dilute size suspension. The temperature of the water is preferably about 36 and that of the molten rosin size about 55 C. at the start of the mixing process in order to obtain the best particle size in the dilute rosin-in-water suspension.

The water is introduced preferably in three portions of approximately equal volume. For

example, for best results the first thirdof the diluent water is introduced through the compartment of the manifold I! having the smallest eflluent area in about 15 to about minutes with the agitator revolving at a rate of about 20 R. P. M. At the end of about 15 to about 20 minutes, the discharge conduit is transferred to the compartment having an intermediate eflluent area and the valve 54 turned to the position in whichthe discharge of the second portion of the diluent water will take place in an intermediate period, say 7 to 10 minutes. When the second third of the diluent water has been introduced into the'converter, the flexible conduit 55 is transferred to that compartment of the manifold I9 which has the largest eflluent area and the valve 54 turned to the position in which the final third of the diluent water is dischargedin the least time, say 3 to 5 minutes. with greater amounts of size gel and correspondingly greater amounts of diluent water, the time increases. However, .for practical purposes, the solid concentrated rosin size gel" 'may be converted to a 501" and diluted to a dilute aqueous size suspension (size milk) in from 25 to '70 ,5 minutes. This time of conversion from the con.- cent-rated solid size "gel" to the .dilute size suspension may be compared with the time of 120 minutes given hereinabove for the conversion of a concentrated aqueous size suspension to a 5 dilute aqueous size. suspension in conventional equipment.

As exemplaryof the practical advantages accruing from the useof the concentrated solid rosin size "gel of the present invention con- 50 verted into a dilute rosin size suspension or size milk by the hereinafter described process in the hereinabove described apparatus, the following tabulation of the sizing effect secured with the dilute size suspension of the present invention as 5 compared with two other commercial size preparations'is given. e

As those skilled in the art recognize a smooth wood-free paper stock of the gram grade is very diflicult to size on one side. Such a paper 60 weighing 63 grams per square meter was sized under controlled conditions with two commercial sizes in comparison with the size milk of the present invention. The composition of the size milks or dilute size suspensions is given below:

Table I V Total rosin Per cent Per cent (rosin free rosin free rosin Size acids+unper per 100 7 saponiiiable) parts size parts total in sire milk milk rosin- A .Q 4a a s4. 0 78.2 Y B 54. 4 13. s 25. 5

Present inventiom. 29. 6. 27. 8 90. 0+

The sizing of the hereinabove mentioned 60- gram wood-free paper was carried out with the above size milks and the sizing efi'ect determined by means of the conventional ink penetration test. A comparison of the sizing effect of the three size milks referred to in Table I is given in Table II:

'1 Designates Unsatisfactory." I Designates "Satlsfactory.

The sizing effect secured with 1.62 grams of the present size is equivalent to the sizing effect of 2.25 grams of size A. Size B is so greatly inferior to the present size that no absolute values have.

been determined. However, it can be readily seen from the above tabulation that size B at least is no better than size A when compared with the present size. This tabulation clearly shows that the use of an amount of the size of the present invention equivalent to about 72% of the amount of size A or B produces equivalent sizing effects. This represents a saving of 28% in the amount of size required.

A tabulation of the sizing effect of the size of the present invention on a one sided Bil-gram wood-containing paper shows similar results:

1 Designates Absolutely unsatisfactory. I Designates Unsatisfactory." 1 Designates "Satisfactory."

While the results obtained with 1.38% of the rosin size of the present invention were-not complete- 1y satisfactory, they were very close to the results obtained with 1.92% of size A: Again the tests show that sizing eflects can be obtained with the size of the present invention equivalent to those of competitive sizes when using only about 70% as much size.

A comparison of the amount of alum required by the optimum amounts of size A and the size of the present invention is clearly shown in Table IV:

I Table IV gram paper 63 gram paper Grams size per grs. paper to produce'satis- I factory size effect Grams of alum per 100 grams paper Grams of alum per 100 grams paper Present size The above tabulation shows that the size of the present invention requires only about 78% as much of alum as other commercial sizes. Furthermore, in view of the fact that the dilute rosin-in-water size suspensions of the present invention contain not more than 10% saponified rosin in comparison with about 75% saponified rosin in prior art sizes (see Table 1)., it follows that when paper is sized at the highest pH' (most alkaline, say pH 6.5) commensurate with satisfactory sizing, the amount of alum required will be less than that required by the prior art sizes andin some instances as much less as 30 to 50%. This highly practical advantage has been confirmed by actual tests.

The sizing effect of the size of the present invention probably is dependent in a large measure upon the size of the particles of rosin in the solid concentrated rosin size gel" of the present invention and the fact that through the critical control of the various factors during conversion, the rosin particles do not agglomerate or flocculate. -In this manner, the rosin size particles are suspended in as finely divided form as possible and thus the maximum sizing effect from a given weight of size is obtained.

Although the present invention has been described in conjunction-with certain preferred embodiments thereof, it is to be understood that variations and modifications can be made. Such variations and modifications are understood to come within the purview of the specification and 'the scope of the appended claims. Thus, it .iS to be understood that wherever the term free rosin is used in the present specification and the appended claims, it'is to be understood that the difference between the total rosin content and the saponified rosin content is meant. In other words, free rosin as used herein designates the total of unsaponified resin acids and unsaponifiable components of rosin contained in the rosin gels and sols embodying the present invention. Similarly, the term alkaline reagen as used in the present specification and the appended claims refers to those reagents which. form water-soluble compounds with the components of the solid rosin size in the amounts present.

We claim;

1. The process for making aqueous dilute rosin size suspensions having a free rosin concentration of at least about 40% and having practically all size particles invisible at a magnification of 2500 diameters which comprises mixing up to about 15% by weight of water with molten rosin in the presence of about 1.0 to about 3.5% by weight of alkali to form a water-rosin mixture, introduc-v ing into said mixture during agitation about 7 to about 9% by weight of casein at a rate approximating that at which said casein is taken up by the water-rosin mixture to form a waterin-rosin emulsion, adding water at a predetermined rate to .said water-in-i'osin emulsion to convert said water-in-rosin emulsioninto a concentrated 'rosin-in-water emulsion maintaining the temperature of said concentrated rosin-inwater emulsion at about 55 C. to prevent cclusion ot the casein by the rosin, and adding diluent water to said concentrated rosin-in-water emulsion at apredetermined rate toprevent the breaking down of said concentrated rosin-inwater emulsion and to obtain a dilute rosin-inwater emulsion whereby dilute rosin-in-water emulsions are obtained containing at least aboutsize particles less than about 1 micron in di-' ameter which comprises establishinga body of molten rosin having a temperature of about 80 to about 100 C., slowly introducing into said molten rosin up to about by weight of water and about 0.1 to about 0.5% by weight of soluble alkali to form a fluid water-rosin mixture, agitating and reducing the temperature 01 said waterrosin mixture to about '75 to about 90 0., introducing during agitation at least two protective colloids selected from the group, consisting of starches, dextrins, animal glue, gelatine and casein at a temperature of about 40 to about 60 C. in an amount equivalent it about 3 to about of the weight of the rosin and at a rate not reater than that at which said colloids are taken i into the water-in-rosin emulsion, allowing a porup by the water-rosin mixture, continuing the agitation until a homogeneous water-in-rosiri emulsion is formed, slowly introducing into said water-in-rosin emulsion up to about 2% or ammonia by weight in the form of about 33% aqua ammonia. allowing an amount 01' said ammonia equal to about 0.8% to about 1.0% by weight 01' the rosin toijreact with said water-in-rosin em'ulsion, and then allowing said water-in-ros emulsion to cool to form a concentrated ater-in- 45, concentrated water-in-rosin gel being suitable rosin gel containing an amount of total alkali only sumcient to combine with all the protective colloids present and about 20% to about of the rosin present and suitable for the prepara-, tion of dilute aqueous rosin suspensions having practically all sizelparticles less than about 1 micron in diameter and containing up to about 93% free rosin.

3."1he process set forth in claim 2 wherein triethanolamine stearate is employed as one of the protective colloids,

4. The process ot making concentrated solid I 5 water-in-rosin size gel suitable for making dilute .aqueous sizing suspensions having practically all size particles less than about 1 micron indiameter which comprises mixing about 1000 kilograms of molten rosin with about '5 kilograms of I soda ash, introducing about 10 kilograms of water into said rosin alkali mixture, adjusting the temperature of said .rosin mass to about to about 100 C and thoroughly-incorporating said water in said rosirf in the presence of said alkali to form 15 agwater-in-rosin emulsion, reducing the temperature of said water-in-rosin emulsion below about ibo' c., introducing into' said waterinrosin emulsion about kilograms of a starch solution containing about 45 to about 55% starch at a '20 rate no greater than that at which the waterin-rosin emulsion takes, up the starch solution,

then adding about 'kilograms of an alkaline solution containing about 45 kilograms of a mixture of about 30 kilograms of casein and about 15 25 kilograms'of animal glue and about 1% kilograms of caustic sodaat a rate not exceeding that at which said alkaline solution is taken up by the water-in-rosin emulsion containing starch, the temperature or said starch solution and said 30 alkaline solution of casein and animal glue being maintained at about 55 C increasing the speed of agitation and continuing the agitation for a short time, introducing; about 50 kilograms of aqua ammonia containing about 33% ammonia tion or said ammonia to react with said water-inrosin emulsion, removing excess ammonia and allowing said water-in-rosinemulsion to .cool to form a solid gel containing about 0.8% to about '40 1.0% of the ammonia whereby a concentrated water-in-rosin gel containing an amount of total alkali only suillcient to combine with all the protective colloids present and about 20 to about 45% of the rosin present is produced, said solid for the preparation of dilute aqueous rosin suspensions having practically all size particles less than about 1 micron in diameter and containing up to about 93% freerosin.

' FRITZ ARLED'I'ER.

ALOIS ALLINA. 

